After acquiring a 08 Mercury Mariner that had been sitting for about a year and wouldn’t start I hooked my scanner up and the only code I’m showing is the one that disables the 12v battery due to the high voltage battery in the back being below 300v. It’s measuring about 234.12 v on my scanner. I’ve read about the small button on the driver side access panel on the side of the dash and after charging the 12v battery on the car overnight the little button just flash’s when I press it some other videos show the light on the button going solid and flashes once complete would anyone happen to know how to get this to work correctly or is there another way to get that voltage back up above 300v so that the code will clear and allow the engine to turn over. Any information would be greatly appreciated. Thank you.

 

I would suggest you verify the suggestion with your local dealership, but here is how I see the problem.
Because the battery SOC (State of Charge) is 20% below the needed reading, that may be the cause for the "Ready" lite not to come on.

If this is the case, your options are to either replace the hi voltage battery or have it removed for charging., providing it is not beyond holding a charge.

In either case the dealership will need to be contacted to determine which path you may need to take.